1. Field of the Invention
The present invention relates to a wing and, more specifically to a wing contoured to match the natural flow of air about the wing, and to a method of designing such a wing.
2. Description of the Related Art
Future supersonic military and commercial aircraft will be required to have high levels of lifting efficiency at subsonic, transonic, and supersonic speeds. Present philosophies for the design of wings vary greatly in addressing multi-point design conditions. A review of existing philosophies of wing design for subsonic, transonic, and supersonic flight reveals both contradictions and similarities.
The contradictions exist mainly between the philosophies for subsonic and transonic (low-speed) cruise design and the schemes for supersonic cruise design. For low speed designs, the tendency is toward a low wing sweep, thick airfoils, and blunt leading edges, with supercritical airfoils being most commonly used. On the other hand, supersonic designs typically employ high-sweep wings with thin airfoils and sharp leading edges. Methods involving linear theory usually provide wing twist and camber.
At maneuvering conditions, designs for both low-speed and supersonic wings utilize variable-camber devices such as leading-edge and trailing-edge flaps. At subsonic and transonic speeds, leading-edge flaps have succeeded fairly well. At supersonic speeds, however, leading-edge flaps have accomplished only minimal benefits in performance. Variable camber devices also have the added drawbacks of increased complexity in design, increased wing weight, and loss in usable volume.
An alternate approach for meeting the required maneuvering conditions is developing a fixed camber wing. Generally, these wing designs have succeeded at their designed lift conditions but have suffered severe camber drag penalties at lower lift conditions.
A conventional uncambered delta wing is conical about the wing tip. Experimental data in "Supersonic Aerodynamics of Delta Wings", NASA TP-2771, March 1988, and theoretical analysis in "The NCOREL Computer Program for 3-D Nonlinear Supersonic Potential Flow Computations", NASA CR-3694, August 1983, show, however, that the flow and pressure loading over the upper surface of a swept delta wing at subsonic, transonic, and supersonic speeds tend to be conical about the apex of the wing. The conical nature of the field of flow on the upper surface of the wing produces favorable and unfavorable pressure fields based on considerations involving drag.